This disclosure relates to methods of making semiconductor devices. More particularly, the disclosed subject matter relates to a method for performing chemical mechanical polishing (CMP), and related equipment.
Chemical mechanical polishing/planarization (CMP) is a key process of smoothing surfaces of semiconductor wafers through both chemical etching and physical abrasion. A semiconductor wafer is mounted onto a polishing head, which rotates during a CMP process. The rotating polishing head presses the semiconductor wafer against a rotating polishing pad. Slurry containing chemical etchants and colloid particles is applied onto the polishing pad. Irregularities on the surface are removed to result in planarization of the semiconductor wafer.
The size of semiconductor wafers has increased to improve throughput and reduce cost per die. For example, in the transition from 300 mm to 450 mm wafer size, the wafer area increases by 125%. The uniformity in smoothness and thickness of the whole wafer becomes more difficult to maintain in these larger wafers.